Fibre optical amplifiers comprising Erbium doped single mode optical fibres, are seen as vital components for future optical communication systems require pumping with high optical powers. Coupling power of the order of 100 mW into a single mode optical fibre from a semiconductor laser is difficult to achieve. This power level is not readily achievable from reliable long lived single lasers operating in monomode, which commonly provide only about 10 mW. One solution which has been applied is multiplexing two orthogonally polarised lasers with a polarisation beam splitter. However this solution only couples the power of two lasers into the fibre. Powers of up to 100 mW are required to pump fibre amplifers.